Common Motoring Mistakes

November 18, 2016

Common Motoring Mistakes – the daft things people do!

A little knowledge is usually worse than knowing nothing about a particular subject. This is certainly true in the automotive world, and explains why people often jump to the wrong conclusion with great alacrity.

Here’s a list of some of the things that you should NOT do:

Top of the list must be removing a thermostat when an engine overheats. This is the correct thing to do if the thermostat has failed in the closed position, but most of the time it makes more sense to first find out why the engine is overheating. Removing the thermostat will cause the engine to take longer to warm-up as well as cause the engine temperature to fluctuate as more or less power is demanded by the driver. This will increase the possibility of the engine wearing out prematurely.

When overheating occurs most people suspect the radiator fan. It’s important to know that this fan is only needed at speeds below about 80 km/h, so that if the engine overheats at cruising speeds the fault must lie somewhere else. Most modern fans are electrically driven so that they don’t rob the engine of power while cruising but are available at low speeds and even after parking, if the engine needs cooling down.

If the gears start to grate while changing it’s natural to suspect the gearbox. Most of the time you will be wrong, because it’s usually a sign that the clutch pedal play is in need of adjustment.

People often fit bigger wheels and tyres because this will cause the engine to rotate slower at any given vehicle speed than before the change. Theoretically this is supposed to result in better fuel consumption, and it occasionally does. Most of the time it doesn’t. The result will depend on the gear ratios chosen by the manufacturer. In most cases the change will be so small that you can hardly measure it.

Many motorists, especially the older ones, tend to stay in the highest gear as much as possible while driving. Engines don’t like that; they feel just as much stress if forced to operate in a high gear as you would feel if you attempt to go up a hill on your bicycle in a high gear. When the car’s speed drop because of the gradient the best (and kind) thing to do is to change to a lower gear. That is what an automatic transmission would do. The lower gears should be used freely in town traffic.

Most people think that an idling engine cannot overheat or wear out because it carries no load. Nothing could be further from the truth. Letting an engine idle for a long time is one of the severe tests that manufacturers put their engines through. An engine can only idle reliably if it gets a slightly richer than normal mixture. Some of this extra fuel does not combust but migrates past the piston rings into the sump where it contaminates the oil. Over time this will increase an engine’s rate of wear.